Stock drum brakes suck, adapting disc brakes can get outta control quick- I've heard drilled brakes are wonderous, marvelous things, but I've also heard of OVERDRILLED brakes. And how they demolish when they shouldn't. So yes, everyone will say "don't do it" But I'll still ask, "Can't it be done carefully?"
When brake rotors are drilled, you are effectively reducing the contact area resulting less less effective braking, not what I would want on MY car.
That's not entirley true. When you brake hard a film of gas is generated as the pads heat up from dragging on the rotor, holes or slots allow the gas to escape making the brakes more effective and less prone to fade. The down side is they can cause micro cracking between holes, but it is far from catastrauphic and I have never heard of a rotor falling apart from the cracks. In fact I have a set of drilled rotors on my Audi right now that have some micro cracks and I don't feel unsafe although the next set will be slotted. If youre talking about drilling a set yourself be careful and have them balanced before putting them on the car. I did a set once and they worked great, but the final cost was about the same as buying a set already drilled.
Drilled brakes rotors on anything less than a race car are functionally USELESS,...though they do look bitchin, if done right. The same goes for slots and cryogenically freezing the rotor.
You do mean drilling brake rotors, and not drilling air holes in drum backing plates, right? Anyway, in my opinion, drilling brake rotors on a street driven car will probably do you about as much good as drilling holes in the front axle. If you've got front discs in good working order and you still can't stop, something's wrong, and it's not a shortage of holes.
I have to fully disagree with you on this. Even though your not racing around and standing on the brakes at bends and corners, there is still a LOT of heat build up driving on the streets especially in traffic. This definitely does help with heat dissipation. Why do you think near all motorcycle have drilled brake rotors. On a car drilled rotor don't work as good as grooved and drilled. I would however say that grooved alone works better than only drilled but the combination works brilliant, even on the street. I had a set of grooved in the front of a 2liter Opel I had a few years ago. That also made the pads last must longer but most of all I never had brake fade due to heat.
Drilled rotors are good for nothing, not even looks in my book because they are totally worthless. The ONLY reason to drill rotors is to reduce the rotating mass when stock rotors are required by the rules. Motorcycles use them because people like the looks and no other reason, same as Porsche, and the new vettes, looks looks looks. Driled rotors, even the factory Prosce ones crack in racing conditions.Cracking means disaster... People used to think pads outgassed and needed to be vented. Modern pads do not have this issue, and drilling or slotting will only cause faster pad wear. Think of a cheese grater. If you don't believe me, show me a racecar that runs drilled rotors during the race, not later on the show circuit... Keith
I agree with Keith on this one partially. I know in NASCAR they sometimes use drilled rotors for qualifying, but never during the race. They do this to cut down on recipricating weight but the rotors will crack during a full race as the rotors reach about 1400 degrees. On a street car, it is pretty useless to drill rotors but slotting can be usefull if it's done right. The thing is, you'd have to be driving like a complete ass-hole all the time to get the performance advantage your paying for. Now for the actual question... When you drill drum brakes you usually only drill the backing plates, not the drums themselves. This vents the heat that builds up in the drum which causes brake fade. This wont make your car stop any faster, but it will make your brakes more reliable when your on them alot i.e. traffic or mountains. Before anyone starts, I got my NASCAR info from Luke Shimp, who was Bobbie LeBonte's head chassis dude until just a couple of years ago.
Another topic that has been discussed to death several times. Do a search for "drilled brake drums" and read. But after Christmas.
If you don't believe me, show me a racecar that runs drilled rotors during the race, not later on the show circuit... Keith[/quote] ?????????? I've never run anything but a drilled rotor.
didnt see it mentioned in this thread yet but the main reason for slotted/drilled DISC brakes is to allow gases to escape when the brakes are stressed..dont know how this works with DRUM brakes,though.. creepy
My dad's friend drilled a set of cast iron discs on his sidecar and they grenaded during a race. He ran headfirst into a wall and killed himself.
I might be quoting an old source, but check out a book called "The Brake Handbook" It contains info on drilled discs and drums. I'm just too damn lazy to go grab the book and quote the info provided. I did not know the gas theory had been abandoned. If your only citation is NASCAR, you might win. Wanna throw other forms of racing in too? Ummmm, I think that'd be rotating weight, or somebody needs to balance their rotors better. Cast iron rotors should not be drilled, they should be slotted. The theory also exists that those same gases build up between the shoe and the drum, which would stand to reason. Just my 2 cents.............. Tim D.
I know a few guys that have drilled there drums on JEEPs. It is my understanding they did it to allow water to get out of the brakes faster and all claim better braking after water crossings. There is some great tech info on how to do this without having to balance the drums afterward on the earlycj5.com site.
You need to understand how brakes work. They convert rotational motion into heat via friction. That heat has to go somewhere, and fast. That path is into the rotor or drum. The larger the mass of the rotor/drum, the more heat that can be put into it. That lack of mass is why early brakes faded so bad, nowhere for the heat to go once it reached a critical point. Now, you wish to tell me that taking mass out will help your braking?? Motorcycles are a different breed. 99% of them use stainless rotors. Stainless does not brake as well as cast iron, especially in the wet (early Kwacker 900 riders recall this, usually with a tale...). The holes are to allow water to go somewhere to allow initial bite. And said water is not shielded from getting ON the rotors, unlike a car... Cosmo
Yea I should really shutup about motorcycles and other solid rotor applications, or water imersion or weird carbon fiber, ceramic etc But Normal automotive brakes, I know. If you don't believe me call Wilwood... Also sorry about hijacking the drum brake thread. I would vent the backing plate if at all possible, my understanding is that is the real problem with drums, the heat has no where to go. So scoops, fans etc would / should help a lot. Also don't forget pad compound, lifetime pads have a horrible friction Coefficient, ceramic pads are the state of the art, more expensive of course...
I won't work. As stated before, you need mass to absorb the heat, which prevents fade. Case in point, go look at a drum brake on a big rig, no holes, no slots, lots of cast iron. And drums are even more susceptible to fracture than rotors...bad idea. The OEM I work for spend's countless hours and millions of dollars trying to improve vehicle braking performance. We would have done this a long time ago if it worked.
Wow, I nominate this thread for misinformation of the week award. Maybe the guys here that actually spent years racing for a living might chime in.... Or maybe I won't since it's off topic from the original question.
Have those of you that say it won't work ever experienced brake fade? Have you installed drilled rotors on that vehicle, then driven hard down the same stretch of hills without any brake fade. I have. I live in the Ozarks. Brakes are important to me.
Well' I,m going to assume the subject here is DISC brakes, since I've never heard of drilling drums (not backing plates, which works). I've built and raced Corvettes in SCCA and Vintage racing for 20years, as well as being a brake engineer for about 10 years. The theory of both drilling and slotting rotors has to do with getting rid of gas buildup from the pads under very high heat situations , and it does work under controlled test conditions. But only under HIGH HEAT - I doubt it would be seen even under very severe road usage. Cracking from the holes is a very real problem - the better rotors have CAST holes, which are not as prone to cracking. Wear is not materially effected with either slotting or drilling, as the pad spans either. I have run drilled rotors on my race Corvettes - not sure I've noted much of a difference except for cracking !! So, the short answer is :looks trick, but don't expect performance increase, and look out for cracking!!
I swear I don't argue on the Internet, and it's Christmas... but, gee, ya think? I don't think anybody said at any point that racing oriuented friction materials are a super idea on the street. Brakes are brakes period. The whole point of them remains the same, regadless if it's a Daytona prototype, a Z06 Vette, or Model A. Point being that lessons learned in extreme conditions, ie racing, have applications in the real world. Avery good example is your statement above about cryo being worthless on the street. Go ask the guy that's bought two or three sets of rotors for his Suburban or one ton pickup, and then got wise and ordered frozen and slotted rotors. It'll be the last set bought, because they're about 1% as likely to warp.
I remember an article I have in a circa 1964 Popular Mechanics that dealt with Stock Car racing and how they modified there cars. They mentioned blueprinting engines and if I remember correctly, about drilling brake drums. This was before your run-of-the-mill American cars started coming with disc front brakes. I have that issue somewhere in that mess I call a closet, but please don't make me get it out. Tonyi
straight from the Wilwood website... Why are some rotors drilled or slotted? Rotors are drilled to reduce rotating weight, an issue near and dear to racers searching for ways to minimize unsprung weight. Drilling diminishes a rotor's durability and cooling capacity. Slots or grooves in rotor faces are partly a carryover from the days of asbestos pads. Asbestos and other organic pads were prone to "glazing" and the slots tended to help "scrape or de-glaze" them. Drilling and slotting rotors has become popular in street applications for their pure aesthetic value. Wilwood has a large selection of drilled and slotted rotors for a wide range of applications.
Getting back to the original question.... I won't say don't do it, but will say why do it? Consider how many bazillion cars have rolled off the assembly lines with undrilled rotors that are capable of stopping 3-4,000 lb. vehicles just fine for 100,000 miles and more with proper care. If this is for a street car (and I assume it is) use your time and money on something else.
You know, you're right. But to give a truly educated response to the query, we would need to know the exact brakes that are being used. For instance, stock '57 Chebby brakes suck balls, and fade faster than snow in Acapulco. But stock '50's Chrysler brakes are really rather good, and just need proper bedding in and follow-up adjustment to work well. As are senior GM models from the same era (Olds, Cadillac, Buick after Al-Fin) ALL Ford drum brakes are criminally bad, the designers should have been arrested and forced to drive Vegas in Chicago during winter, and they should never be allowed to touch a pencil again, ever. You can see I'm feelin' charitable, seein' as it's Christmas an' all... Cosmo
If you read my post again note that I said undrilled rotors. I was speaking of disc brakes only. To be more clear: I was saying that if he were to upgrade to disc brakes there was really no need to drill the rotors as the factory rotors work fine. (this is assuming the "donor" brakes are from a similar or larger size /weight vehicle.) You are preaching to the choir here as I will always choose discs' over drums, traditonal or not, I like to stop.
Yea do it. Just don't go for looks. Basically all you need is some small holes to let the hot gasses out from between the shoe and the drum.
Directly from Baer's site: "Will slotting or cross-drilling my stock rotors improve my car's stopping performance? DEFINITELY NOT! Crossdrilled or slotted rotors do produce a strong visual appeal behind a modern open wheel, and they do have a performance edge when pad outgassing occurs. Outgassing occurs at extreme temperatures when the bonding agents that hold the pad material together break down into a gas form. This gas creates a pneumatic barrier between the rotor and the pad, reducing friction. Crossdrilling or slotting creates a path for the outgassing that occurs during extreme braking conditions. However, these conditions can virtually never be reached on the street! Short of a complete system, performance brake pads, a proper Teflon lined braided stainless steel hose set and quality brake fluids are the only direct replacement upgrades that can be combined to deliver measurable stopping improvements in the context of direct replacement components on the OE brake system. " But to answer the question: if you do have it done, take it to CH Topping in Long Beach, CA to have them drilled. Or find a professional place to do it locally.
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